Cleaning apparatus

ABSTRACT

A cleaning apparatus for removing residual toner particles from a transfer member used in an electrostatic reproduction machine. Toner powder images are deposited on a sheet of support material secured releasably to the transfer member, the sheet is stripped therefrom, and the cleaning apparatus actuated to remove residual toner particles adhering to the transfer member.

United States Patent m] I v Draugelis et a1.

[ June 25, 1974 1 CLEANING APPARATUS [75] Inventors: Vaidevutis C. Draugelis, Rochester;

Otto R. Dole, Walworth, both of NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Mar. 27, 1972 [21] Appl. No.: 238,553

[52] US. Cl. 355/17, 355/4 [51] Int. Cl G03g 15/00 [58] Field of Search 355/15, 17,4; 15/301,

[56] References Cited UNITED STATES PATENTS 2,986,466 5/1961 Kaprelian 3 55/4 3.583,807 6/1971 Pollock 355/4 3.600.081 8/1971 Egnaczak 355/15 3,615,813 10/1971 Clarke 355/15 3,713.736 1/1973 Sargis 355/15 Primary E.\'aminerJohn M. Horan Attorney, Agent, or Firm-James J.- Ralabate; H. Fleischer; C. A. Green [57] ABSTRACT A cleaning apparatus for removing residual toner particles from a transfer member used in an electrostatic reproduction machine. Toner powder images are deposited on a sheet of support material secured releasably to the transfer member, the sheet is stripped therefrom, and the cleaning apparatus actuated to remove residual toner particles adhering to the transfer member.

3 Claims, 4 Drawing Figures CLEANING APPARATUS The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it in tended to be limiting as to the scope of the invention in any way.

BACKGROUND OF THE INVENTION This invention relates generally to an electrostatic printing machine, and more particularly concerns a cleaning apparatus for removing residual toner particles from a transfer member after a sheet of support material having developed powder images thereon has been stripped therefrom.

In a typical electrostatic reproducing machine, a photoconductive surface is charged to a substantially uniform potential and then exposed to a flowing light image of an original to be reproduced. As a consequence, the exposure discharges the photoconductive surface in accordance with the light intensity reaching the surface, thereby creating a latent electrostatic image on the photoconductive surface. Development of the latent electrostatic image recorded on the photoconductive surface is achieved by toner particles. The toner particles are brought into surface contact with the photoconductive surface and held thereon electrostatically in a pattern corresponding to the latent image. Thereafter, the developed image is transferred to a suitable sheet of support material, such as paper, which is secured releasably to a transfer member. In the transfer step, substantially all of the toner particles adhere to the support material to form the image thereon, however, a very small percentage of the toner may remain on the transfer member.

' With the advent of multi-color reproduction involving the utilization of processing components adapted to produce a series of electrostatic images in which each image represents a particular color in the original, there is a need to transfer successive partial color toner powder images onto a sheet of support material in superimposed registration. For this reason, the transfer member recirculates the sheet of support material through a plurality of transfer cycles. Incidentally, it will be appreciated that a black and white or single color such as a red, cyan, magenta or yellow, reproduction requires only a single transfer step, whereas a multi-color reproduction may necessitate a plurality of such transfer steps. Hence, it follows that the amount of residual toner particles remaining adhered to the transfer member after the formation of a multi-color copy may be appreciably greater than after the production of a single color copy. For example, in a three color subtractive system, cyan toner particles, magenta toner particles, and yellow toner particles are successively transferred to the copy paper. The copy paper is secured to the transfer member, e.g. a rotating drum, and recirculated thereon for three successive cycles. After each cycle the toner particles developed on the photoconductive surface are transferred to the copy paper. Thus, the formation of a multi-color copy from a multi-color original requires three successive transfer operations, each transfer operation being for specific toner particles, i.e. cyan, magenta or yellow. It is evident, therefore, that this substantially increases the potential amount of residual toner particles left adhering to the transfer member after the sheet of support material has been stripped therefrom. The residual toner particles will accumulate from copy to copy and degrade subsequent copies in that additional residual toner particles would adhere more readily to the nonimage side of the copy paper. In the case of a transparency, the projected image would include the unwanted residual toner particles as well as the intended image. Furthermore, unwanted residual toner particles on the non-imaged side of an opaque copy would degrade a subsequent image formed thereon via a duplexing process, i.e. copying on both sides of the copy sheet. This is of particular concern in multi-color reproduction wherein unwanted toner particles may distort the color and blur the image.

Accordingly, it is the primary object of the present invention to improve multi-color copies formed by an electrostatic reproducing machine through the reduction of accumulated residual toner powder particles on the transfer member.

SUMMARY OF THE INVENTION Briefly stated and in accordance with the present in vention, there is provided a cleaning apparatus for use inan electrostatic printing machine having a transfer member. The transfer member is arranged'to have secured releasably thereto a sheet of support material, and to move the same in recirculating fashion to receive a series of toner powder images, each toner powder image corresponding to a particular color in the original. After the toner powder images are deposited on the sheet of support material, in superimposed registration, the sheet is removed from the transfer member.

In accordance with the present invention, the'cleaning apparatus includes means for removing toner particles which remain adhered to the transfer member. Moreover, provision is made for means to actuate the toner removing means only after the sheet of support material has been stripped from the transfer member.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIG. 1 is a schematic perspective view of an electrostatic printing machine embodying the features of the present invention;

FIG. 2 is a schematic perspective view of a cleaning apparatus used to remove residual toner particles adhering to the transfer member of the printing machine illustrated in FIG. 1;

FIG. 3 is a fragmentary elevational view depicting the mechanism used in the present invention to move the brush of the cleaning apparatus into its operative position; and

FIG. 4 is a fragmentary sectional elevational view illustrating the brush and flicker bar used in the cleaning apparatus of the present invention.

While the present invention will be described in connection with a preferred embodiment and method associated therewith, it will be understood that it is not intended to limit the invention to that embodiment and method. On the contrary, it is intended to cover all altematives, modifications and equivalents as may be in cluded within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION For a general understanding of the illustrated electrostatic printing machine, in which the present invention may be incorporated, continued reference is had to the drawings wherein like reference numerals have been used throughout to designate like elements. FIG. 1

' schematically illustrates the various components of a machine for producing multi-color copies from a color original. As in all electrostatic systems as well as a xerographic machine of the type illustrated, a light image of a document to be reproduced is projected onto the sensitized surface of a photoconductive member to form a latent electrostatic image thereon. Thereafter, the latent image is developed with toner particles to form a powder image corresponding to the latent image on the photoconductive surface. The powder image is then electrostatically transferred'to a sheet of support material, e.g. plain paper, to which it may be fixed by a suitable fusing device, whereby the powder image is caused permanently to adhere to the support surface.

The printing machine depicted in FIG. 1 employs a photoconductive member, such as rotatably mounted drum 10, having a photoconductive surface l2thereon. Photoconductive surface 12, preferably, is formed of a material having a relatively panchromatic response to white light. Drum rotates in the direction indicated by arrow 14 to move photoconductive surface 12 sequentially through a series of processing stations.

First, photoconductive surface 12 passes through charging station A which has positioned thereat a corona generating device, indicated generally at 16, extending transversely across photoconductive surface 12. Corona generating device 16 charges drum surface 12 to a relatively high substantially uniform potential.

The charged drum surface 12 is next rotated to exposure station B which includes a moving lens system, generally designated by the reference numeral 18, and a color filter mechanism, shown generally at 20. An original document 22 is stationarily supported upon a transparent viewing platen 24 wherein successive incremental areas of original 22 are illuminated by means of a moving lamp assembly shown generally at 26. Lens system 18 is adapted to scan successive areas of illumination at platen 24 and .to focus the light on photoconductive surface 12. Lamp assembly 26 and lens system 18 are moved in timed relation with photoconductive surface 12 to produce a flowing light image of the original on photoconductive surface 12 of drum 10 in a nondistorted manner. During exposure, filter mechanism interposes selected color filters into the optical light path of lens 18. The color filters operate on the light passing through the lens to record a latent electrostatic image on the photoconductive surface corresponding to a specific color of the flowing light image of the original.

Subsequent to the recording of the latent electrostatic image on photoconductive surface 12, drum 10 is rotated to development station C which includes three individual developing units generally indicated by the reference numerals 28, 30 and 32, respectively.

The developing units are all of a type usually referred to in the art as a magnetic brush development unit. Typically, in a magnetic brush development system, magnetizable developer material including carrier granules and toner particles are continually brought through a directional flux field to form brush of developer material. Developer particles are continually moving to provide the brush continually with fresh developer material. Development is achieved by bringing the brush into contact with photoconductive surface 12. Each of the development units 28, 30 and 32, respectively, apply toner particles corresponding to the complement of the specific color separated latent electrostatic image recorded on photoconductive surface 12, each toner particle being adapted to absorb light within a preselected spectral region of the electromagnetic wave spectrum corresponding to the wavelength of light transmitted through the filter. For example, a latent image forrned by passing the light image through a green filter will record the magentas as areas of relatively high charge density on photoconductive surface 12 while the green light rays will cause the charge density on photoconductive surface 12 to be reduced to an ineffective development level. The magentas are then made visible by applying green absorbing magenta toner particles to the latent image recorded on photoconductive surface 12. Similarly, a blue separation is developed with yellow toner particles while a red separation is developed with cyan toner particles.

After development, the now visible image is moved to transfer station D where the image is transferred to a sheet of final support material 36, such as plain paper amongst others, by means of a transfer member, Le. a bias transfer roll shown generally at 34. The surface of transfer roll 34 is electrically biased to a potential having a magnitude and polarity sufficient to electrostatically attract toner particles from photoconductive surface 12 of drum 10 to sheet 36. Transfer roll 34 is adapted to secure releasably a single sheet of final support material 36 for movement in a recirculating path, the roll being arranged to move in synchronism with photoconductive surface 12 enabling support material 36 to receive successive toner powder images of the original. The aforementioned steps of charging the photoconductive surface, exposing the photoconductive surface to a specific color of the flowing light image of the original, developing the latent electrostatic image recorded on the photoconductive surface with appropriate toner particles, and transferring the toner powder image to a sheet of final support material, e.g. a transparency or opaque copy sheet, are repeated a plurality of cycles to form a multi-color copy of a color original.

After the last transfer operation, support sheet 36 is stripped from roll 34 and transported on endless conveyor 50 to a fixing station F where a fuser, indicated generally at 38, coalesces the transferred image to support sheet 36. Thereafter, sheet 36 is advanced by endless conveyors 52 and 54 to catch tray 40 for subsequent removal by an operator.

The last processing station in the direction of rotation of drum 10, as indicated by arrow 14, is cleaning station E. A rotatably mounted fibrous brush 56 is positioned in cleaning station E and is maintained in contact with photoconductive surface 12 of rotating drum 10 to remove residual toner particles remaining thereon after each transfer operation.

After the sheet of support material has been removed from transfer roll 34 and prior to the securing thereto of a subsequent sheet of support material, cleaning of transfer roll 34 is initiated. The cleaning apparatus, indicated generally at 41, includes actuating means, de-

picted generally at 43 comprising means 51, to move the toner removing means, illustrated generally at 45, from an inoperative position to an operative position for removing residual toner particles adhering to transfer member 34. While the present invention has been described in connection with actuating means 43 including moving means 51, one skilled in the art will appreciate that the invention is not necessarily so limited. The actuating means may merely be a suitable switch or logic element designed to energize the toner removing means at the appropriate time in the machine cycle, while the toner removing means may be operative in its normal position rather than requiring movement from a non-operative to an operative position.

Toner removing means 45 utilizes brush 44 rotatably mounted in housing 42 in conjunction with an exhaust means such as a vacuum and filtering system for removal of toner particles from the transfer roll surface. Housing 42 is indexed toward transfer roll 34 and positions brush 44 in engagement therewith for one revolution of the transfer roll. Toner removing means 45 is only operative when the support material is removed from transfer roll 34, and, at all other times, will remain in an inoperative position with brush 44 spaced preferably about one inch away from transfer roll 34 to provide the necessary clearance for recirculating the support sheet material on transfer roll 34. Moving means 51 includes cam 46 which is mounted rotatably in frame 68 of the' printing machine, and is driven by motor 48 to pivot housing 42. Housing 42 pivots to position brush 44 in contact with transfer roll 34 when support material 36 is removed therefrom.

Referring now to FIG. 2, cleaning apparatus 41 is shown therein with brush 44 engaging transfer roll 34 as it rotates in the direction of arrow 35. Housing 42 is pivotably mounted within frame 68 which is attached to the printing machine. Cam member 46 is driven by motor 48 and engages housing 42 at pin 47 which is secured thereon. Moving means 5] also includes biasing means or spring 58 for resiliently urging housing 42 into engagement with cam 46. Spring 58 has one end thereof secured to frame 68 and the other end thereof attached to housing 42. As cam 46 rotates it pivots housing 42 from its non-operative position wherein brush 44 is spaced approximately one inch from transfer roll 34 to its operative position wherein brush 44 contacts the surface of transfer roll 34 to dislodge residual toner particles remaining thereon. Brush 44 is rotatably mounted within housing 42 and is driven by a four pole, split capacitor motor indicated by the reference numeral 70, which preferably rotates at about 1625 revolutions per minute. Pulley system 72 reduces the speed of brush 44 preferably to about 700 revolutions per minute. Preferably, housing 42 has longitudinally extending aperture therein to enable a portion of brush 44 to extend outwardly therefrom and engage transfer roll 34. During the transfer roll cleaning operation, transfer roll 34 is spaced from photoconductive surface 12, preferably about /8 of an inch. This permits transfer roller 34 to rotate freely and only engage brush 44, thereby readily permitting cleaning apparatus 41 to remove residual toner particles from transfer roll 34. Housing 42 is a die casting preferably made from a suitable metal or elastomeric material, and is operatively connected to filter means 61 via toner-tight conduit 60. Conduit 60 is a flexible hose made from a suitable elastomeric material such as rubber or plastic and adapted to permit housing 42 toarticulate from the inoperative position to the operative position wherein brush 44 engages the surface of transfer roll 34. Filter means 61 includes filter box 62 which forms a chamber for housing filter bag 64 having its open end connected to hose 60. Filter box 62 is made from a substantially rigid material such as a suitable molded plastic.

Vacuum blower 66 is secured to filter box 62 at the end opposed from the entrance of conduit 60. When filter bag 64 is substantially empty, blower 66 preferably draws 40 cubic feet per minute of air and maintains a 0.88 inch of water static vacuum. However, when filter bag 64 is substantially full, blower 66 preferably maintains an air flow of 30 cubic feet per minute and a vacuum of 1 inch of water static vacuum. Filter bag 64 is of a tri-layer construction. The outer layer of filter bag 64 is a 54. inch thick fiberglass, the middle layer 3/16 inch polyester, and the inner layer 1 inch thick modiglass. f Turning now to FlG.3, there is shown moving means 51 for pivoting housing 42 from an inoperative position in which brush 44 is spaced from transfer roller 34 to an operative position wherein brush 44 is in engagement with the surface of transfer roll 34. Housing 42 is pivotably mounted to frame 68 which is integral with the printing machine. Spring 58 serves to resiliently urge housing 42 into engagement with cam 46. One end of spring 58 is secured to frame 68 and the other end thereof is contacting pin 49 attached to housing 42. As cam 46 rotates, it engages pin 47 also attached to housing 42 and pivots housing 42 against the action of spring 58 to position brush 44 in contact with the surface of transfer member 34. Cam 46 is a double lobed cam which is driven by cam indexing motor 48 (FIG. 2). Cam indexing motor 48 is actuated by suitable logic circuitry within the printing machine to pivot housing 42 and position brush 44 in contact with transfer roll 34 at the appropriate time in the machine cycle, i.e. after support material 36 has been separated therefrom.

Referring to FIG. 4, which depicts flicker bar 74 engaging brush 44 in housing 42 brush 44 is preferably made from polypropylene fibers extending from a substantially solid core and is adapted to rotate at 700 rpm as hereinbefore described. Brush 44 is designed to engage transfer roll 34 (FIG. 2) preferably with an interference of about 0.094 inches. Moreover, flicker bar 74 interfers with the brush fibers to bend the fibers so that as the fibers are released by the flicker bar they tend to fling the toner particles therefrom. As the residual toner particles are flicked away from the brush fibers, the vacuum system evacuates the toner particles therefrom through a conduit into filter bag 64. Flicker bar 74 is preferably made from a suitable substantially rigid elastomeric material such as tetrafluoroethylene.

When a plurality of copies of one original document are to be reproduced on the printing machine, cleaning apparatus 41 is activated to remove toner particles from the transfer roll 34 after all of such copies have been made. However, this is but one embodiment of the present invention and cleaning apparatus 41 may be readily activated after each copy is reproduced. Thus, when one copy of an original document is being made, cleaning apparatus 41 removes toner particles from transfer roll 34 after all of the partial images have been transferred to support material 36, and support material 36 has been removed therefrom. Whereas, in

the event of a plurality of copies being made from the same original, cleaning apparatus 41 removes toner particles from transfer roll 34 after the last of such copies has been removed from transfer roll 34.

From the foregoing, it is apparent that the cleaning apparatus of the present invention improves multicolor copies produced on an electrostatic printing machine by removing the residual toner particles remaining on the transfer roll. This prevents the accumulation of toner particles on the non-image side of the copy and enables transparencies and duplex copies to be reproduced with multi-color characteristics of repeatedly high quality.

It is, therefore, evident that there has been provided, in accordance with this invention, an apparatus and a method for cleaning the transfer roll of an electrostatic printing machine that fully satisfies the objects, aims and advantages set forth above, While this invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

What is claimed is:

l. A cleaning apparatus for use in a printing machine having a transfer member adapted to secure releasably thereto a sheet of support material for movement in a recirculating path to receive a plurality of successive toner powder images of an original to be copied, including:

rotary driven brush means;

means for housing said brush means, said housing means having a longitudinally extending aperture therein enabling a portion of the periphery of said brush means to extend outwardly therefrom;

filter means;

a toner-tight conduit connecting said housing means with said filter means for conducting residual toner particles from said housing means to said filter means;

means for exhausting air and residual toner particles from said housing means through said conduit to said filter means;

a cam member mounted rotatably on the printing machine;

biasing means for resiliently urging said housing means into engagement with said cam member; and

means for driving said cam member to pivot said housing means and move said brush means from an inoperative position spaced from the transfer member to an operative position in contact therewith after the sheet of support material having the plurality of successive toner powder images deposited thereon has been stripped therefrom, said brush means being adapted to dislodge residual toner particles adhering to the surface of the transfer member.

2. A printing machine of the type having a photoconductive member for recording a latent electrostatic image which is developed with toner particles in image configuration, and a transfer member adapted to secure releasably thereto a sheet of support material for movement in a recirculating path to receive a plurality of successive toner powder images, in superimposed registration, to form a multi-color copy of the original .to be copied, including:

rotary driven brush means;

means for housing said brush means, said housing means having a longitudinally extending aperture therein enabling a portion of the periphery of said brush means to extend outwardly therefrom;

filter means;

a toner-tight conduit connecting said housing means with said filter means for conducting residual toner particles from said housing means to said filter means;

means for exhausting air and residual toner particles from said housing means through said conduit to said filter means;

a cam member mounted rotatably on the printing machine;

biasing means for resiliently urging said housing means into engagement with said cam member; and

means for driving said cam member to pivot said housing means and move said brush means from an inoperative position spaced from the transfer member to an operative position in contact therewith after the sheet of support material having the plurality of successive toner powder images deposited thereon has been stripped therefrom, said brush means being adapted to dislodge residual toner particles adhering to the surface of the transfer member.

3. A m'ulti-color electrophotographic printing machine, including:

a photoconductive member;

means for charging said photoconductive member to a substantially uniform potential;

means for projecting a substantially single color lightimage on said photoconductive member to record thereon a substantially single color electrostatic latent image;

means for depositing toner particles, substantially complimentary in color to the single color light image, on the electrostatic latent image recorded on said photoconductive member;

a transfer member operatively associated with said photoconductive member for movement in synchronism therewith, said transfer member being arranged to have secured releasably thereto a sheet of support material for receiving a plurality of Suecessive toner powder images from said photoconductive member;

means for removing toner particles adhering to said transfer member; and

means for controlling said toner removing means,

said controlling means inactivating said toner removing means in response to the sheet of support material being secured to said transfer member and activating said toner removing means in response to the sheet of support material with the plurality of successive toner powder images deposited thereon, being stripped therefrom permitting said toner removing means to remove toner particles remaining on said transfer member. 

1. A cleaning apparatus for use in a printing machine having a transfer member adapted to secure releasably thereto a sheet of support material for movement in a recirculating path to receive a plurality of successive toner powder images of an original to be copied, including: rotary driven brush means; means for housing said brush means, said housing means having a longitudinally extending aperture therein enabling a portion of the periphery of said brush means to extend outwardly therefrom; filter means; a toner-tight conduit connecting said housing means with said filter means for conducting residual toner particles from said housing means to said filter means; means for exhausting air and residual toner particles from said housing means through said conduit to said filter means; a cam member mounted rotatably on the printing machine; biasing means for resiliently urging said housing means into engagement with said cam member; and means for driving said cam member to pivot said housing means and move said brush means from an inoperative position spaced from the transfer member to an operatiVe position in contact therewith after the sheet of support material having the plurality of successive toner powder images deposited thereon has been stripped therefrom, said brush means being adapted to dislodge residual toner particles adhering to the surface of the transfer member.
 2. A printing machine of the type having a photoconductive member for recording a latent electrostatic image which is developed with toner particles in image configuration, and a transfer member adapted to secure releasably thereto a sheet of support material for movement in a recirculating path to receive a plurality of successive toner powder images, in superimposed registration, to form a multi-color copy of the original to be copied, including: rotary driven brush means; means for housing said brush means, said housing means having a longitudinally extending aperture therein enabling a portion of the periphery of said brush means to extend outwardly therefrom; filter means; a toner-tight conduit connecting said housing means with said filter means for conducting residual toner particles from said housing means to said filter means; means for exhausting air and residual toner particles from said housing means through said conduit to said filter means; a cam member mounted rotatably on the printing machine; biasing means for resiliently urging said housing means into engagement with said cam member; and means for driving said cam member to pivot said housing means and move said brush means from an inoperative position spaced from the transfer member to an operative position in contact therewith after the sheet of support material having the plurality of successive toner powder images deposited thereon has been stripped therefrom, said brush means being adapted to dislodge residual toner particles adhering to the surface of the transfer member.
 3. A multi-color electrophotographic printing machine, including: a photoconductive member; means for charging said photoconductive member to a substantially uniform potential; means for projecting a substantially single color light-image on said photoconductive member to record thereon a substantially single color electrostatic latent image; means for depositing toner particles, substantially complimentary in color to the single color light image, on the electrostatic latent image recorded on said photoconductive member; a transfer member operatively associated with said photoconductive member for movement in synchronism therewith, said transfer member being arranged to have secured releasably thereto a sheet of support material for receiving a plurality of successive toner powder images from said photoconductive member; means for removing toner particles adhering to said transfer member; and means for controlling said toner removing means, said controlling means inactivating said toner removing means in response to the sheet of support material being secured to said transfer member and activating said toner removing means in response to the sheet of support material with the plurality of successive toner powder images deposited thereon, being stripped therefrom permitting said toner removing means to remove toner particles remaining on said transfer member. 